It is commonplace to pour mortar screeds on the ground in order to flatten, level or grade a floor and/or coat underfloor heating in order to then receive the upper layers (all floor types: tile flooring, soft flooring, floating wood or glued-down flooring, etc.).
After pouring, setting and surface drying of the screeds, the appearance of a surface film of several hundredths of millimeters thick, formed by calcium hydrate-based particles rising to the surface, is often observed. The fine film has folds and inesthetical flakings and considerably reduces the several adherence capacities of finishing materials intended subsequently to cover the screeds, such as plaster, adhesive ceramic, paint, various sealers or other adhesive coatings.
This type of film is also observed at the surface of other hydraulic compositions such as self-compacting concrete (SCC), a concrete capable of compacting itself in even complex and constricted formwork under the sole effect of gravity.
To obtain sufficient adhesion, it is necessary to brush, scratch or sand the surface in order to remove the film before beginning the bonding work of a covering or finishing. This work is time-consuming and expensive.
It is known from U.S. Pat. No. 6,849,118 to use an admixture comprising a fatty alcohol and an anti-shrinkage agent of the alkylene oxide type to prevent the formation of surface dust caused by the anti-shrinkage agent.
A composition is also known from WO 95/04008 that comprises C14 to C22 fatty alcohols, preferably in the form of an emulsion, in particular to inhibit efflorescence in the cement compositions. Efflorescence differs, however, from the described particle film of in that it results from a calcium salt carbonation reaction at the surface of cement compositions.
Due to their low melting point and hydrophobic character, fatty alcohols are, however, difficult to disperse. In solid form, they quickly agglomerate under heat or during storage under their own weight, making them difficult to use.
The use of a fatty alcohol emulsion is also known from U.S. Pat. No. 3,486,916, for limiting the evaporation of water on exterior surfaces.
Finally, the use of an admixture in powder form, comprising a fatty alcohol and an anti-caking agent is known from FR2948930, for reducing the formation of films on horizontal surfaces. Like all finely divided organic compositions, this type of composition may be flammable and/or explosive, since it comprises fatty compounds, in particular fatty alcohols in finely divided powder form. It is therefore necessary to take precautions in the storage and handling of the product (for example, grounding of installations).